The preparation process of N,N'-dialkylalkanediamine has been known for a long time, and many processes have been proposed. For example, J. uber die Fortshritteder Chemie, 389(1859) has reported a process for preparing N,N'-diethyl-1,2-ethanediamine by reacting dibromoalkane with alkylamine.
A process for obtaining N,N'-dimethyl-1,2-propanediamine has been described in J. Chem. Soc., 214(1947).
Further, processes for preparing N,N'-dimethyl-1,3-propanediamine and N,N'-dimethyl-1,2-ethanediamine have also been known.
Japan Laid Open Patent SHO 57-120570 has disclosed a process for preparing 1,3-dimethyl-2-imidazolidinone via N,N'-dimethyl-1,2-ethanediamine as an intermediate by reacting 1,2-dichloroethane, water, liquid methylamine and carbon dioxide in an autoclave.
Further, a reaction of dichloroalkane with primary lower alkylamine has been found as a process for preparing N,N'-dialkylalkanediamine. Various investigations have been carried out on the reaction. For example, a process for carrying out the reaction in the presence of a nickel compound and/or copper compound and a process for carrying out the reaction substantially in the absence of moisture have been proposed in Japan Laid Open Patent SHO 62-129256.
These processes for preparing N,N'-dialkylalkanediamine by reaction of dihaloalkane and alkylamine can provide the desired product in a high yield and thus are favorable processes.
The processes can provide N,N'-dialkylalkanediamine in a yield of 80 to 85%. However, 1 to 5% of cyclic dialkyldiamine and 9 to 13% of trialkylalkanetriamine are formed as impurities at the same time. The whole amount of impurities including other by-products is considerably large. As a result, enhancement of equipment has been required for the purification of thus obtained N,N'-dialkylalkanediamine.
Consequently, as to the preparation of N,N'-dialkylalkanediamine, it has been desired to develop a process which can inhibit formation of cyclic dialkyldiamine, trialkylalkanetriamine and other impurities and can provide high purity N,N'dialkylalkanediamine in a high yield. It has also been demanded that N,N'-alkylalkanediamine is produced by such a process in order to simplify the purification operation.